From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91801C4320A for ; Mon, 2 Aug 2021 07:02:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7044860E76 for ; Mon, 2 Aug 2021 07:02:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232465AbhHBHCe (ORCPT ); Mon, 2 Aug 2021 03:02:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232297AbhHBHCc (ORCPT ); Mon, 2 Aug 2021 03:02:32 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81FD9C06175F; Mon, 2 Aug 2021 00:02:23 -0700 (PDT) Date: Mon, 2 Aug 2021 09:02:18 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1627887740; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vAzZg5McgFlmYcY3vHHS7joGLgzy1wAKFe4TyqSJf4Q=; b=UxfSwwajYsRzsd7ojnKcpaNOmN7Qek2ryXEVUm8tDjiwsxo1gyiHQR/Jvx2TWhmL6GWrTt Z1MKfWCASnaLymQN4Qw/LsROvaRBUKdLzUAgK5Xzx72p3n+WeP5BfxDBVS8n1Bgohkn5uV lKP5HbhfWgsWWr2Me2UvivJpdpM1qw32GVpgfGcJrehtxJRfNm3NkZLUXruzByJWJ0hRgm c6UIrQ+uQ6hVi9FtWnGaz7pxvaQg2VEnclcTAn/x8nQTapwgC2lytRfF0j4gRmtx9ErcPW SBDqPg3pFWafifT4R/YFxuI4tM2WNqTXF+G7i2z20AKXuwtH72lAC52hw2tOBQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1627887740; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vAzZg5McgFlmYcY3vHHS7joGLgzy1wAKFe4TyqSJf4Q=; b=7o11tUdlH+hzGPbzr8mVCq+/Ij2napnOuvPAKqRc1dtUi3P8oY5JrMB9I7fo0Z6MtII0Rt 8x4wAdyQzs5hQNDw== From: Sebastian Andrzej Siewior To: Mike Galbraith Cc: Thomas Gleixner , LKML , linux-rt-users@vger.kernel.org, Steven Rostedt , Peter Zijlstra Subject: Re: v5.14-rc3-rt1 losing wakeups? Message-ID: <20210802070218.5js3exubjxvsicx6@linutronix.de> References: <20210730110753.jvli6alm63h5lefy@linutronix.de> <2ae27233ab091d09a7d1e971a47144b40dd51fa0.camel@gmx.de> <87pmuzsf1p.ffs@tglx> <6fce881efc3d8c24a5172528fe1f46ec2ddc0607.camel@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-08-01 17:14:49 [+0200], Mike Galbraith wrote: > On Sun, 2021-08-01 at 05:36 +0200, Mike Galbraith wrote: > > On Fri, 2021-07-30 at 22:49 +0200, Thomas Gleixner wrote: > > > > > > > > First symptom is KDE/Plasma's task manager going comatose.=C2=A0 No= tice soon > > > > > > KDE/Plasma points at the new fangled rtmutex based ww_mutex from > > > Peter. > > > > Seems not.=C2=A0 When booting KVM box with nomodeset, there's exactly o= ne > > early boot ww_mutex lock/unlock, ancient history at the failure point. >=20 > As you've probably already surmised given it isn't the ww_mutex bits, > it's the wake_q bits. Apply the below, 5.14-rt ceases to fail. Take > perfectly healthy 5.13-rt, apply those bits, and it instantly begins > failing as 5.14-rt had been. Given what you have replied to the locking thread/ ww_mutex_lock_interruptible() may I assume that the wake_q bits are fine and it is just the ww_mutex? Sebastian